Grinding or pulverizing mill



(No Model.) 2 sheets-sheet v1.` J. HUNT.

GRINDNG 0R PULVERIZING MILL.

No. 493,164, Patented Mar. 7, 1893.

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GRINDING 0R PULVERIZING MILL.

No. 493,164. Patented Mar. 7,1893.

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JOSEPH HUNT, OF ALLENTOWN, PENNSYLVANIA.

SPECIFICATION forming part of Letters Patent No. 493,164, dated March '7, 1893.

Application led April 6, 1892. Serial No. 428,020. (No model.) v

.To all whom t may concern:

Be it known that I, JOSEPH HUNT, a citizen of the United States, and a resident of Allentown, Pennsylvania, have invented certain Improvements in Grinding or Pulverizing Mills, of which the following is a specifica- My invention relates to that class of grinding or pulverizing mills in which the material to be ground is in a dry state and in which the grinding or pulverizing action is effected by rolls running against the inner face of a fixed ring, the objects of my invention being to so construct a grinding or pulverizing mill of this class as to insure the effective contact of the grinding rolls with the inner face of the ring, whether the mill is run fast or slow, to effectually prevent the escape of the finely ground or pulverized material from the mill casing, or its access to the roll bearings, to

provide for the ready feeding of the mill, and4 to so hang the grinding rolls as to permit of the ready application or removal of the same when desired, and lessen the friction due to the rotation of the same on their axes.

In the accompanying drawings:-Figure l, is a vertical section of a grinding mill constructed in accordance with my invention. Fig. 2, is a plan View of the same. Fig. 3, is a sectional view illustrating a modification of the invention; and Fig. 4, is a view partly in longitudinal section and partly in elevation illustrating the method of supporting the roll shafts in their bearings. Fig. 5, is asectional plan View on the line 1 2, Fig. 4; and Fig. 6, is a sectional plan View on the line 3-4, Fig. 4.

A represents the base or foundation of the mill upon which is mounted an annular troughlike structure B supporting aring D,an outer casing Fsurrounding said ring D and structure B, and said outer casing F having at the top an inwardly projecting ring F2 which overlaps the ring D.

The base structure A of the mill has a ste bearing ct for thev lower end of a central vertical shaft G which passes through a bearing a at the top of an upwardly projecting oentral portion or hub formed upon the trough structure B, and upon the upper end of said shaft is mounted a dished plate J constitutopenings d to either of which the pivot d can be adapted so as to shift the fulcrum of the hanger as desired. Each hangerK terminates at the inner end in an enlargement K forming a bearing for the shaft M of the grinding roll, and said enlarged inner portion of each hanger is adapted to a radial recess or pocket f formed in the dished portion of the roll carrier J as shown in Fig. 2, so that as said carrier is rotated, the hangersK and the rolls M will be caused to rotate therewith, the rear wall of Veach pocket bearing against the adjacent face of the bearing K so as to cause the said bearings and their shafts to rotate around the axis of the shaft G thereby relieving the pivot pins d for the hangers K of all or a large portion of the strain caused by the performance of this duty. Each roll M is su pported vertically in its hanger K by means of a collar secured to the upper end of the shaft M and bearing upon the top of the enlarged inner end K of said hanger, said collar being preferably formed as shown in Figs. 4 and 5, that is to say, by means of two half collars g, g', each having a flange t' adapted to an annular groove t" formed in the shaft some distance below the top of the same, these half collars being held together by an encircling ring h resting upon external shoulders h formed on the half collars as shown in Fig. 4. Between the bottoms of the collars and the top of the hanger K are interposed one or more washers k, preferably of antifriction metal. A collar of this sort can be readily applied or removed and is therefore preferable to a single collar secured in place by a transverse pin or equivalent means.

Extending from the top 0f the cap ring F2 to a point close to the bottom of the top flange IOO of the roll carrier J are two annular screens I), P', the inner screen being perforated and the outer screen being imperforate and having also at the top an imperforate ring in with packing strip m bearing against the underside of the flange of the carrier J, the space between the two screens being in communication with the annularspace F between the ring D and casing F through openings 7i formed in the ring F2.

From the bottom of the roll carrier J depends an annular frame S which is substantially similar in contour to the trough structure Il and is adapted to run close to the bottom of the latter, said frame being provided with the usual inclined blades or plows S which, as the frame is rotated, lift the material from the trough and throw it up in front of the rolls M and onto the internal screen P, which is, by preference, inclined outward from bottom to top so that the particles projected onto said screen will roll down the same and thus provide for a more effective sifting of the fine particles from the coarse particles than would be effected by a vertical screen or bya screen inclined inward from bottom to top. The screening of the fine particles from the coarse particles is also materially facilitated by the fan-like action of the projections or pockets jformed upon the roll carrier J, the use of a special fan for the purpose being dispensed with. The particles caught between the rolls M and the ring D are crushed thereby, it being understood that the rolls M are pressed firmly against the ring D by reason of the centrifugal force Adue to the rotation of the series of rolls around the common axis supplied by the shaft G, each roll being also caused to rotate upon its own axis by reason of such intimate contact with the ring D. It will be observed that the pivot of each roll hanger K is outward beyond the axis of the roll, so that there is a natural tendency of the roll to bear against the ring D independently of the centrifugal force, hence mills, especially those havingheavy rolls, can be run with good effect at low speed as is desirable in some cases. The fine particles passing through the meshes of the internal screen P are discharged from the space between the two screens through the openings n and passage I" into a receiving chamber T beneath the trough structure B from which they are in turn discharged through the spout T by means of a rotating carrying plate s carried by the shaft G.

The roll carrier J has elongated openings t to permit the slight vibrating movement of the shafts M which results in the operation of the mill, and in order to prevent the escape of the finely powdered material through these openings each of them is covered by a plate t which tits snugly to the shaft M andis free to move to and fro with the same. The escape of finely powdered particles from the top of the mill is effectually prevented by the packing strip 'm' which bears against the underside of the top flange of the roll carrier, so that the mill is practically dust tight, an important consideration in drygrinding mills of the character to which my invention relates. It will be noted, moreover, that the bearings for the roll shafts are entirely outside of what maybe termed the casing of the mill, so that the access of dust to these bearings, and the attendant wear and inconvenience are effectually prevented.

In order to provide for the ready feeding of the mill, I employ an axial hopper IV with spout leading outward from the bottom of the same and passing through the bottom of the roll carrier J at a point between the central hub of the same and the wall of the dished portion, preferably as close to the latter as possible, so that the centrifugal action aids the flow of the material from the hopper through the spout, the feeding device, of course, rotating with the roll carrier, but the hopper, occupying an axial position, so that the material can be readily fed into the same while the mill is running.

In practice I prefer to make the feed spout WV in spiral form, as shown, although a straight spout may be used if desired.

In Fig. 3, I have shown a modification of my invention in which the inner portions K of the roll hangers have short arms Kiwith lugs w bearing in a groove formed in the top of the carrier J so that the fulcrum of each hanger is closer to the axis of the roll shaft than in the construction shown in Fig. 1, and said roll swings outward almost in a direct line against the grinding ring. In this case also I have shown springs interposed bctween the hangers K and adjustable studs on the hub of the roll carrier so that the action of said spring supplements the centrifugal action or the outward swing of the rolls in pressing said rolls against the grinding ring.

Having thus described my invention, I claim and desire to secure by Letters Patent- I. The combination in a grinding or pulverizng mill, of the grinding ring, a series of rolls in Contact with the inner face of said rin g, a rotating roll carrier located above the grinding ring, and having a central vertical portion with radial recesses 01' pockets therein and hangers for the shafts of the grinding rolls, said hangers being pivoted to said carrier and adapted to the pockets therein, so as to have a driving contact with the walls of said pockets, substantially as specified.

2. The combination in a grinding 0r pulverizing mill, of the grinding ring, a series of rolls in contact therewith, a dust-proof casing for the said grinding ring and rolls and a rotating roll-carrying structure having roll bearings wholly outside of the casing of said dust-proof mill, whereby dust is prevented from gaining access to said bearings, substantially as specified.

3. The combination of the grinding ring, the grinding rolls running in contact with the inner face of the same, and hangers for said IOC IIO

rolls pivoted at points outward beyond the axial line of the rolls, whereby the latter normally swing into contact with the ring, substantially as specified.

4. The combination ofthe grinding ring, the series of rolls in contact with the inner face of said ring, a rotating roll carrier 1ocated above the ring, an internal perforated and external imperforate screen mounted above the grinding ring and a packing ring carried by said screen structure and bearing against the roll carrier, so as to form a dustproof joint therewith, substantially as specied.

5. The combination of the grinding ring, the grinding rolls, the screen above the ring, and a rotating roll carrier having projecting pockets which serve as vanes to direct a cur- JOSEPH HUNT.

Witnesses WINsLoW Woon, CHAS. F. BALLIET. 

